My mom has it
She has a major fear of contamination. Actually partially led to my parents' divorce. Dad works in wastewater treatment (usually chemical waste). At the worst of it he wasn't allowed to sleep in their room, he had to sleep on the couch that wasn't used often. His clothes had to be washed separately from everything else. She's got a major fear of nuclear stuff too. We cannot say we're going to "nuke" something if we're putting it in the microwave. It sends her into practically a panic attack. If something is on the news about nuclear stuff, she runs from the room. I've been to the beach twice with my mom ever (I'm 19) because there's a nuclear power plant near the ocean in NH, and she's afraid that all of that stuff is leaking into the ocean. Now she's never banned me from going to the beach; she just barely ever goes.
Whenever we leave the house for an extended amount of time she can't be the last person out. Someone has to check the house AFTER she goes out to the car. We have to check and make sure that the toilets have stopped running (if they've been flushed), the stove/oven/coffee maker is off, and that all the windows are closed/locked and the lights are turned off. We have turned around on multiple occasions because she's not sure that the garage door is down. And no, our word is not enough.
Laundry is a nightmare. Fuzzy stuff can't be washed with nonfuzzy stuff. Even red stuff that has been washed 50 times still can't be washed with pink things, because she panics that it'll bleed. Needless to say months go by between when I can wear reds. She flipped when she found out that at school I do two loads of laundry every two weeks: one lights, one darks. She separates everything by color and texture. She will wash jeans with greys, and pastel blues/greens/purples (and sometimes even pinks) together. But everything is much more separated than the way I do laundry
She washes her hands an unbelievable amount of times a day. To the point where her hands are always dried out and bleeding, and she has to use lotion year round
She's afraid her shoes or pants or whatever have bugs in them, or that they're contaminated. In other words, when she goes to put shoes on, she shakes them out first, and looks in them. Getting up from the toilet is an ordeal, because she shakes out her pants, or shorts, stands up, looks, sits down, shakes them out, etc.
Most days it's not debilitating for her. I know all of these things sound extreme, but most days, although she does them, they're not severe. But if she's nervous about something, or hears something on the news about something nuclear, she goes into panic mode and things get worse.